当我试图用数据库数据填充java swing中的表时，出现java.lang.NullPointerException错误消息

我试图用数据库表中的数据填充JavaSwing中的jTable。以下是我设置连接的代码

    package DBController.database;

    import java.sql.*;

    public class DBController {
private Connection con;

public void setUp(String dsn) {
    try {
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");          
    } catch (Exception e) {
        System.out.println("Load driver error");
    }
    try {

        String s = "jdbc:odbc:" + dsn;
        con = DriverManager.getConnection(s, "", "");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public ResultSet readRequest(String dbQuery) {
    ResultSet rs = null;
    try {
        Statement stmt = con.createStatement();
        rs = stmt.executeQuery(dbQuery);
    } catch (Exception e) {
        e.printStackTrace();
    }
    return rs;
}

public int updateRequest(String dbQuery) {
    int count = 0;
    try {
        Statement stmt = con.createStatement();
        count = stmt.executeUpdate(dbQuery);
    } catch (Exception e) {
        e.printStackTrace();
    }
    return count;
}

public void terminate() {
    try {
        con.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

}

下面是我试图为sql语句编写的代码

    public boolean retrieveDiscussion() {
    boolean success = false;
    ResultSet rs = null;
    DBController db = new DBController();
    db.setUp("IT Innovation Project");
    String dbQuery = "SELECT * FROM forumTopics WHERE topic_description = '" + description
            + "' and topic_category = '" + category
            + "' and topic_title = '" + title 
            + "' and topic_by = '" + postedBy + "'";
    rs = db.readRequest(dbQuery);
    db.terminate();
    return success;
}

以下是用户界面中“我的表”的代码

    public static void main(String[] args) throws Exception {
    // The Connection is obtained

    eForumTopics topics = new eForumTopics();
    topics.retrieveDiscussion();

    // It creates and displays the table
    JTable table = new JTable(buildTableModel(null));
    JOptionPane.showMessageDialog(null, new JScrollPane(table));

    // Closes the Connection
}
public static DefaultTableModel buildTableModel(ResultSet rs)
throws SQLException {

    ResultSetMetaData metaData = rs.getMetaData();

    // names of columns
    Vector<String> columnNames = new Vector<String>();
    int columnCount = metaData.getColumnCount();
    for (int column = 1; column <= columnCount; column++) {
        columnNames.add(metaData.getColumnName(column));
    }

    // data of the table
    Vector<Vector<Object>> data = new Vector<Vector<Object>>();
    while (rs.next()) {
        Vector<Object> vector = new Vector<Object>();
        for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
            vector.add(rs.getObject(columnIndex));
        }
        data.add(vector);
    }

    return new DefaultTableModel(data, columnNames);

    }

错误消息。那我该怎么办？提前谢谢。

看起来这个bug是

JTable table = new JTable(buildTableModel(null));

---

请给出错误的完整堆栈跟踪，即行号等。同时创建一个带有随机值等的表，因为我们无法测试线程“main”java.lang.NullPointerException中没有表ETCEException的代码，该线程位于kioskeForum.ui.eForumDiscussion.buildTableModel（eForumDiscussion.java:271）的kioskeForum.ui.eForumDiscussion.main（eForumDiscussion.java:262）但在我删除空值后，buildTableModel将有错误。如果我从public static DefaultTableModel buildTableModel中删除结果集rs，则之后的所有“R”都将有错误。实际上，我从某个网站获取了代码。这些是完整的代码。public static void main（字符串[]args）抛出异常{//连接已获得ResultSet rs=stmt.executeQuery（“从产品_信息中选择*）；//它创建并显示表JTable table=new JTable（buildTableModel（rs））；JOptionPane.showMessageDialog（null，new JScrollPane（table））；//关闭连接}然而，在那里的stmt，错误消息要求我投射一些东西。我不知道投射对象是如何工作的。即使我研究也没有答案。

JTable table = new JTable(buildTableModel(null));